Liquid fuel combustion apparatus with previous vaporization



Oct. 13, 1964 J. SCHOTSMAN LIQUID FUEL COMBUSTION APPARATUS WITHPREVIOUS VAPORIZATION 2 Sheets$heet 1 Filed July 5. 1961 FIG.2

INVENTOR. J n fc/wfxman Oct. 13, 1964 J. SCHOTSMAN LIQUID FUELCOMBUSTION APPARATUS WITH PREVIOUS VAPORIZATION Filed July 5, 1961 2Sheets-Sheet 2 United States Patent 3,152,634 LIQUID FUEL COMBUSTIQNAPPARATUS WITH PREVIOUS VAPORIZATION Jan Schotsman, Dieren, Netherlands,assignor to N.V.

Emailleerfabriek De Ijsel, Dieren, Netherlands, a corporation of theNetherlands Filed July 5, 1961, Ser. No. 121,901 Claims priority,application Netherlands, July 12, 1960, 253,701 5 Claims. (Cl. 158-71)The invention relates to a liquid fuel combustion apparatus, in whichfuel is first guided through a vapor chamber which is disposed near theheater but out of direct contact with flames whereby fuel is preheated.The device may be provided with a safety overflow.

Heating devices of this type are generally known, in these knownapparatus the vapor chamber is kept away from direct contact with theflames to try to prevent the temperatures of the fuelfrom running up sohigh that it reaches the cracking point, or, when admixing air, toprevent a spontaneous ignition of the vaporized fuel.

In most constructions the vapor chamber is situated beside or under theburner and forms a unitary construction with it. Conduction heat, or acombination of radiation heat and conduction heat, is utilized.

A drawback of this construction is that the temperature can run up toohigh, so that additional measures are necessary. For instance, the vaporchamber may be partially filled or provided with a number of partitions,screen plates or cooling ribs.

However, various safety measures are necessary which render theapparatus not only much too expensive but also extremely vulnerable.

Further, it is known to provide a tube-shaped vapor chamber out ofdirect contact with the flames, by placing a ring or spiral windingplaced beside the burner, but above it creating a danger of overheating.

From British Patent 133,688, a vapor chamber is known which is placedbeside the flame base and comprises a plurality of spiral windings, sothat while it is true that the lowermost winding lies within the rangeof the least intense radiation, there is a chance of overheating at thehigher points which will cause an increase in the temperature ofevaporation.

For starting a heating apparatus various devices for preheating thevapor chamber are used, for instance a spirit tablet, a fuse, anauxiliary burner, an electric element and the like. Starting with theaid of an electric element is very attractive, because of simplicity andease of regulation. However, preheating should also be effected verygradually, because otherwise there would arise a risk of cracking out orof spontaneous ignition when air is admixed. In the generally knownapparatus, in which, then, an electric heating element is applied, thislatter extends over the entire length of the vapour chamber, so that therelatively cold inflowing fuel suddenly enters the heated zone.

For Swiss Patent No. 275,954, there is described a vapor chamber whichis situated within direct range of the flames, and in this chamber anelectric heating element is utilized, which does not extend over theentire length of the vapor chamber; however, the part which is notheated by this element is situated near the vapor- 3,152,634 PatentedOct. 13, 1964 "ice (gas-) outflow opening, so that at the other end therelatively cold fuel still suddenly enters the heated zone, andafterwards may condense before the exhaust the exhaust.

Finally, all heating devices with pre-vaporization (-gasification) havethe additional drawback that, quite irrespective of the preheatingmethod which is applied, the fuel supply must always be reduced untilthe burner is able to keep the evaporation going and it is only thenthat the fuel supply can be fully opened.

It is an object of the invention to eliminate the above describeddrawbacks and by applying a number of meas ures to obtain a reliable andsafe heating apparatus.

It is another object to make use only of the laterally directedradiation of the flame while completely avoiding flame convection.

It is a further object to start the vaporization of the fuel with theaid of an electric heating element situated inside the vaporizationchamber whereby the fuel supply can be completely opened immediately theheating element is switched on.

The means by which the objects of the invention are obtained are fullydescribed with reference to the accompanying drawings which illustrate apreferred em- .bodiment of the invention.

FIG. 1 shows a front view of the combustion apparatus the front platebeing removed.

FIG. 2 shows a transversal cross-section along the line IIII in FIG. 1.

FIG. 3 is an elevation, enlarged and in detail, of the right side of theapparatus, of FIG. 1.

FIG. 4 is an enlarged sectional view, showing the relationship of aburner, vaporization chamber and reflector in detail.

The combustion apparatus 1 is provided in a known way with a liquidlevel regulator 2, which is fed by conduit 3 coming from a liquid tank.

The liquid level regulator 2 is connected by the conduit 4 to thepro-vaporization chamber 5, which is provided with an overflow safety 6,the highest point of which just projects a little above the liquid levelin the regulator 2, so that it is impossible for fuel to flow into theburner when the flame is extinguished. With reference to FIG. 3, it canbe seen that if the burner were extinguished, liquid fuel will flow intothe chamber and up into the overflow device but will not flow downconduit 8 which is disposed at the top of the safety and which in turnis located higher than regulator 2. Vaporization chamber 5 has a fuelentrance end 5a and a fuel exit end 5b and is positioned at a slightincline rising with the fuel flow so that the vaporized fuel may beallowed to flow freely away beyond the liquid section. A light metalgauze filling (not shown) can be provided in the vaporization chamber ina known way as an extension of the vaporization surface for thepromotion of the successive evaporation and for neutralization of theoccasional fluctuations in the velocity of the inflowing fuel. In thevaporization chamber 5 is provided an electrical heating element 7 overmaximally three quarters of the length of the prevaporization chambercalculated from the vapor (gas) outflow opening. This makes a verygradual heating of the liquid fuel possible, whereby, moreover the fuelsupply can be completely openedimmediately after the heating element isswitched on. By the conduit 8 the vapor is guided to the injector 9,which is mounted in the air suction mouth-piece 10, which possesses ageneratrix 11, slightly declining towards the mixing chamber 12 underthe burner 13, which can be built up from porous incandescent bodies.The air suction mouth-piece 10 is connected to the double bottom 22 forthe primary supply of air. Opposite the vaporization chamber 5 isprovided a reflector 14. The overflow safety 6 is provided at theoutside with a fireproof and heat insulating wall 15. The bottom of thepre-vaporization chamber is also provided with a local heat insulation15, in order to prevent occasional cooling by the secondary air fanningpast it. The combustion chamber is limited at the rear.

side in aknownway by a draught funnel 1;7-which serves to lead air of aslow as possible a temperature to the cooling system 18.- Finally, theapparatus is providing in a known way with a chimney connection 19,containing amongother things an automatic draught regulator 20. and adraught cut-ofl 23. 21 is a double-walled screenagainst radiation on theliquid level regulator 2.

The burner Isis, placed in an oblique position in such a way thatthewhole of the incandescent surface is visible through a window in thefront wall not rendered in the drawing.

In the liquidfuel heating apparatus withgpre-vaporization(gasification), according to the invention not only are theaforedescribed drawbacks eliminated, but by applying a number ofmeasures a reliable and safe heating apparatus is obtained, which inaddition to this is of simple. construction.

In the disclosed construction use is made only of the laterally directedradiation of the flame, while completely avoiding flame convection. Inaddition to the ideal vaporization temperature being well maintainableat this position. of-the vapor chamber is relation to the burner plane,the said working temperature is only slightly reduced even at lowpositions of burner capacity because the radiation near the lower rimremains relatively high. Besides, the special manner in which theelectric heating element is provided makes very gradual heating of theliquid. fuel. possible, whereby the fuel supply can be completely openedas soon as the heating element is switched on.

By positioning a thermostat in the combustion apparatus in a known way,which thermostat causes the, elecric preheating to be switched of whenthe working temperature is reached, it is possible to save current andthe whole of the operation is restricted to the mere opening of fuelsupply. and the switching on of the electric current, which is veryimportant for a device intended for domestic use.

The vapor chamber is, positioned at a slight incline rising with thefuel flow so that the vapor (gas) of the most volatile components may beallowed to flow freely away beyond the liquid section ending before themiddle of the length.

' With the combustion apparatus, according to the invention.vaporization is effected at the lowest possible temperature, that is tosay near, but well below, the final boiling point of the fuel fractionsburned, so that premixing with air is possible, without the risk ofspontaneous ignition of the mists caused when mixing.

In addition to this, it is possible to provide the apparatus with areflector which is mounted opposite the part of the vapor chamber whichis not directly exposed to radiation, so that this part of the vaporizerdoes indeed receive radiation from the lower regions, but not from thehigher regions of the burner flame. In this case a low flame effectivelyemits relatively more radiation, to the benefit of the. maintenance ofthe right temperature equilibrium. A slight readjustment of thisreflector also offers the possibility of readjusting the workingtemperature if a somewhat heavier fuel should render this necessary.This measure is characterized in that a hollow cylindrical reflector isadjustably provided parallel to and opposite the part of the vaporchamber which is turned away from the flame base.

Although the vapor chamber is heated at the front side directly by theflame radiation and at the back side via a reflector, there still is achance of the vapor chamber being locally cooled by secondary combustionair fanning past its bottom side, so that the temperature equilibriumcan be disturbed. In order to prevent this inadvertent cooling, thebottom of the vapor chamber is provided with a heat insulating material.

Furthermore, a generally known overflow safety can advantageously beapplied, so that it is impossible for fuel to flow into the burner whenthe flame is extinguished.

However, a special measure should be taken to take care that, on the onehand the temperature in this safety is maintained, but on the other handcannot be influenced from the outside, because, naturally, the highestpoint of this safety should be at a level with or a little above theliquid level in the float chamber of the regulator and consequently cancome with the flame range. For this purpose, this safety overflow isaccording to the invention characterized in that it is provided with awall which is fireproof and insulates against heat.

Although by the application of the above-described measures it iseffected that atv the start the heating is as gradual as. possible andthe evaporation temperature is as low as possible, yet it isunavoidable, when starting, for a few drops of liquid fuel tocondenseout and be carried away with the vapor (gas) flow and drip down whenissuing from the injector. In order to prevent the possibility of thesedrops flowing away outside, the heating apparatus according to thepresent invention has provisions for guiding said drops to the bottom ofthe mixing chamber, where they evaporate later, on under the influenceof the heat of the burner. I-his measure is characterized in that theair suction pipe which is connected to the, mixing chamber and in whichthe injection is mounted, has a generatrix which slightly declinestowards the bottom, of the mixing chamber.

In the combustion apparatus according tothe invention a minimum amountof mixing air is guaranteed by the impulse from the vapor jet, which isamplified by the natural draught created in the heated body of the stoveitself. Both are substantially identical to the fuel demand, so thatover a fairly large regulation range there is little change in thecomposition of the mist.

Thev close connection to a draught-supplying chimney, so necessary inother combustion apparatus, in this construction is superfluous and'evenundesirable. The rigid draught interrupter required in gas stoves willfrequently suflice.

A second argument against draught aid'is based on the consideration,that no depression with respect to the immediate air-containingsurroundings may be caused in the mixing chamber at any price.

This vagrant air immediately causes flareback combined with the formingof soot in the mixing chamber.

The combustion apparatus according to the invention is extremely simpleto operate, is completely safe and practically makes no noise.

I claim:

1. Liquid fuel combustion apparatus comprising a burnerhaving a planarburner element, said planar element being inclined such that the, planethereof is disposed at an angle relative to. a horizontal plane of thecombustion apparatus, a tubular vaporization chamber having fuel exitand entrance ends and disposed adjacent the lowermost portion of saidplanar burner element and out of direct contact with a burner elementflame, said tubular vaporization chamber being inclined at a slightangle with respect to a horizontal plane of the apparatus such that saidfuel exit end is higher than said fuel entrance end, an electricalheating element disposed longitudinally of the tubular vaporizationchamber and extending no more than three-fourths of the length of saidtubular vaporization chamber calculated from the fuel exit end thereof,fuel injection means including an inlet for directing air and vaporizedfuel to said burner element, and conduit means for conducting fuel fromsaid vaporization chamber to said fuel injection means.

2. Liquid fuel combustion apparatus as claimed in claim 1 includingliquid level regulating means to regulate the supply of fluid to saidvaporization chamber.

3. Liquid fuel combustion apparatus as claimed in claim 2 including asafety overflow means provided at the fuel exit end of said tubularvaporization chamber.

4. Liquid fuel combustion apparatus as claimed in claim 3 including areflector adjustably mounted parallel to the vaporization chamber on theside thereof opposite said 15 burner element.

References Cited in the file of this patent UNITED STATES PATENTS238,634 Billings Mar. 8, 1881 1,175,493 Williams Mar. 14, 1916 1,238,003Crook Aug. 21, 1917 1,741,725 McKeown Dec. 31, 1929 2,507,464 De AndradeSo May 9, 1950

1. LIQUID FUEL COMBUSTION APPARATUS COMPRISING A BURNER HAVING A PLANARBURNER ELEMENT, SAID PLANAR ELEMENT BEING INCLINED SUCH THAT THE PLANETHEREOF IS DISPOSED AT AN ANGLE RELATIVE TO A HORIZONTAL PLANE OF THECOMBUSTION APPARATUS, A TUBULAR VAPORIZATION CHAMBER HAVING FUEL EXITAND ENTRANCE ENDS AND DISPOSED ADJACENT THE LOWERMOST PORTION OF SAIDPLANAR BURNER ELEMENT AND OUT OF DIRECT CONTACT WITH A BURNER ELEMENTFLAME, SAID TUBULAR VAPORIZATION CHAMBER BEING INCLINED AT A SLIGHTANGLE WITH RESPECT TO A HORIZONTAL PLANE OF THE APPARATUS SUCH THAT SAIDFUEL EXIT END IS HIGHER THAN SAID FUEL ENTRANCE END, AN ELECTRICALHEATING ELEMENT DISPOSED LONGITUDINALLY OF THE TUBULAR VAPORIZATIONCHAMBER AND EXTENDING NO MORE THAN THREE-FOURTHS OF THE LENGTH OF SAIDTUBULAR VAPORIZATION CHAMBER CALCULATED FROM THE FUEL EXIT END THEREOF,FUEL INJECTION MEANS INCLUDING AN INLET FOR DIRECTING AIR AND VAPORIZEDFUEL TO SAID BURNER ELEMENT, AND CONDUIT MEANS FOR CONDUCTING FUEL FROMSAID VAPORIZATION CHAMBER TO SAID FUEL INJECTION MEANS.